siemenkehitys

Siemenkehitys, the Finnish term for seed development, refers to the intricate biological process that begins after fertilization in flowering plants and gymnosperms. It is a crucial stage in the plant life cycle, leading to the formation of a mature seed capable of germinating and producing a new plant. This process involves a series of coordinated cellular events, including cell division, differentiation, and growth.

The development begins with the zygote, the fertilized egg cell, which undergoes rapid division to form the embryo. Simultaneously, the endosperm, a nutritive tissue, develops to provide sustenance for the growing embryo. The ovule's integument, the protective outer layer, transforms into the seed coat, which shields the embryo and endosperm from environmental damage and desiccation.

During seed development, the embryo differentiates into distinct structures, including the radicle (embryonic root), hypocotyl (embryonic shoot below the cotyledons), and cotyledons (seed leaves). The number and nature of cotyledons vary between plant groups; monocots typically have one cotyledon, while dicots have two. The endosperm accumulates storage reserves, such as starches, proteins, and lipids, which will be utilized during germination.

The mature seed is a remarkable package of life, containing the embryo, stored food reserves, and a protective seed coat. Its development is tightly regulated by hormonal signals and genetic factors, ensuring the production of viable offspring. The cessation of seed development is often triggered by desiccation, leading to a dormant state where the seed can survive unfavorable conditions until germination is initiated by appropriate environmental cues like moisture, temperature, and light.